Modular counter carry circuit

ABSTRACT

Herein described is a carry circuit used with pulse counters which convey carry information from one module of a digit counter to an associated module as, for example, in a decade counter. A commutator associated with one digit is energized by a pair of brushes which are rotated by the count wheel thereof. The count wheel is designed to start its rotational indexing movement only after termination of an input count pulse, thereby causing the brushes to rotate only when current has ceased to be applied to the circuit. The counter includes, for example, an add coil and a subtract coil. The commutator includes a segment coupled to the add coil on the next preceding digit counter and a segment coupled to the subtract coil of the next preceding digit coil. When the index wheel is moved into a nine position, the brushes and commutator are simultaneously aligned to provide for actuation of the next decade counter simultaneously with the first decade counter upon receipt of an additional add pulse. Upon removal of such pulse, the first decade wheel moves from nine to zero, while the second decade wheel moves one increment. Stepping of additional decade wheels are likewise provided for. Likewise, receipt of a subtract pulse when the index wheel is moved into a zero position would cause a reverse rotation in applicable decade wheels due to the particular design and alignment of the brushes and commutator.

United States Patent 1191 Dec. 11, 1973 Burton [54] MODULAR COUNTER CARRY CIRCUIT [57] ABSTRACT ventor: Joh 5- B 11349 Elderwood Herein described is a carry circuit used with pulse L05 Angeles, Calif- 90049 counters which convey carry information from one [22] Filed: Man 15, 1972 module of a digit counter to an associated module as,

for example, in a decade counter. A commutator assol l PP 234,976 ciated with one digit is energized by a pair of brushes Related Us Application Data which are rotated by the count wheel thereof. The count wheel is designed to start its rotational indexing [63] fgy of movement only after termination of an input count pulse, thereby causing the brushes to rotate only when [52] Us. CL 235/92 C 235/92 Ev 235/92 EA current has ceased to be applied to the circuit. The p 235/92 counter includes, for example, an add cod and a sub- 51 1111.01 G06m 1/276, G06m 3/14 The ncludes a e'" 9? 58 Field 6: Search 235/92 BA 92 0 PM the add the next Pecedmg 235/92 EV 133 A 1, counter and a segment coupled to the subtract co1l of the next preceding digit coil. When the index wheel is [56] References Cited moved into ill nine positilon, tget brushesI arfrd commp tator are s1mu taneous y a rgne o prov1 e or ac ua 1on UNITED STATES PATENTS of the next decade counter simultaneously with the 2,973,145 2/196l Daniel 8! al. 2.35/92 EA first degade counter upon receipt of an additional add 312381359 3/1966 P etalm- 235/92 pulse. Upon removal of such pulse, the first decade 'ggs gig 33g wheel moves from nine to zero, while the second de- 3'115573 12 1963 Nemeufil... 11:: 235 92 0 i wheel mves stePping f 3:112:06! 11 1963 Ernest et al.... 235/92 (3 decade wheels are Pmvded 3,202,802 1 8/1965 Shoor 235 92 c Wise, receipt of a Subtract Pulse when the index Wheel 3,6 5 1 5/1972 Takashi Miyagawa et 1 235 92 EA is moved into a zero position would cause a reverse Primary ExaminerMaynard R. Wilbur rotation in applicable decade wheels due to the particular design and alignment of the brushes and commu- Assistant Examiner-Joseph M. Thesz, Jr. aw All JhJ.P t,J.

army 0 n 05 a r 10 Claims, 2 Drawing Figures O i l 1 38 32 5a 22 I i 54 f PATENIEDBEM 1 197a mini! 1 MODULAR COUNTER CARRY CIRCUIT CROSSREFERENCES This application is a continuation-in-part of my copending patent application, Ser. No. 66,036, filed Aug. 21, 1970.

BACKGROUND OF THE INVENTION A. Field of the Invention This invention relates to carry circuits and more particularly to a novel and improved carry circuit and structure used in modular by-directional counters for communicating carry pulses from one digit of a decade counter to a next digit. With further particularity, the invention relates to a novel apparatus which communicates add or subtract pulses to the succeeding or preceding modules at predetermined transition numbers depending upon the direction of rotation of the counters and a determination of a count pulse to the counter.

B. Discussion of the Prior Art In the prior art many attempts have been made to provide an effective count-up/count-down mechanical counter capable of rotating a counter or number wheel in a direction dependent upon the pulses applied thereto. The count pulses are applied to predetermined input terminals. The number wheel in response to these pulses is advanced a certain amount. For example, if two pulses are applied in a positive going direction, or' to a positive input means, the number wheel is rotated in a forward direction two increments. Conversely, if two pulses would be provided in a negative going direction or to a seqond input means, the number wheel is retracted two increments.

One of the present problems involved in modular counters described above is carry pulse commutation. By modular counters is meant a different count wheel is used to designate different digits in a decade counting system which includes a plurality of such decades. It becomes necessary at the end of a digit count from, say, the units decade to the tens decade, that at the end of a nine on a count-up pulse in a count-up mode, the next preceding counter must be enabled by a pulse from the preceding counter. Thus, when the units counter, for example, is on a nine, the next pulse applied thereto should ordinarily indicate a 10. Thus, the units digit counter rotates to zero and thereafter the tens unit rotates to one.

Heretofore bi-directional counters operating in the add-subtract modes have been developed, but until the present invention no device has yet been conceived which operates bi-directional with full carry in each mode. The present invention is the first fully electromagnetic add-subtract modular counter with carry. In the past such carry technique was essentially performed by mechanical, geneva-type gear mechanisms. Alternately, means were provided for the opening and closing of contacts during pulse application to a decade counter simultaneously with the application of the pulse and movement of the commutator and count wheels. This design caused sparking to occur with attendant wearing of brushes and contacts. Additionally, this switching during pulse application resulted in erroneous readings and imprecise movement of the decade wheels.

It has been discovered that when pulse actuation and transfer takes place, only when the commutator and count wheel are stationary, a more reliable and highly accurate electrical carry or subtract operation is accomplished, something heretofore not accomplished in the prior art.

Copending patent application Ser. No. 227,972, entitled Bi-Directional Counter, by the same inventor as this application and assigned to the present assignee, thoroughly describes a bi-directional counter which would be useful in the present invention and operates in the above described manner. Such a counter as is described and set forth in the copending patent application has the inherent advantage of counting pulse termination prior to movement of the counter wheel.

The present invention makes use of the fact that the count wheel of one decade carries a set of brushes which rotate with the count wheel of the first decade and serves to energize the indexing mechanism of a succeeding decade by use of a unique commutator disc. The direction of rotation of the brushes against the commutator is dependent upon whether the device is in the add mode or in the subtract mode. If it is in the subtract mode, a pulse is communicated to the preceding decade at the zero to nine transition and if in the addition mode, a pulse is communicated to the succeeding decade at the nine to zero transition, but in each case, only while the count wheel and brush are in a static state.

Recent designs, specifically as set forth in the aforementioned copending patent application uses the novel technique of indexing only after the indexing pulse is terminated. When such an indexing is used, during carry, each subsequent module receives a full actuating pulse and switching is accomplished with no loss of pulse during the switching operation. The circuit to the next module is closed (in the add mode) when the carry contact reaches nine and only after removal of the index pulse. The next coil is energized through this contact when the 10th pulse arrives and cocks the armature against a spring in accordance with the copending patent application. The spring provides a drive to switch the contacts and index number wheel at the end of the 10th pulse. In the subtraction mode the action is the same but the carry occurs between zero and nine.

SUMMARY OF THE INVENTION To overcome the present difficulties, the bidirectional counter with the carry circuit of the present invention was developed. The bi-directional counting mechanism includes an electrically actuated armature having two independent movements. More particularly, the armature moves in a semi-circular direction with a rocking motion. A pair of pawls are provided each being moved by the armature, with the direction of rotation depending upon the electrical pulses applied to the coils associated with the armature. A ratchet wheel is included which includes teeth adapted to be engaged by the pawls to index in one direction by one pawl and in a second direction by the other pawl.

It has been found that the best time to move the ratchet wheel is after termination of the initial count pulse. The initial count pulse in effect cocks the armature carrying the pawls. Termination of the pulse allows a return spring mechanism to cause the armature to return to its neutral position. During such return, one of the pawls which operatively engages the ratchet wheel causes the wheel to rotate an index position.

A cam is integrally formed on each one of the pair of pawls and is adapted to engage the ratchet teeth of the ratchet to clear the pawls over the teeth. The pawls push the ratchet wheel and number wheel through the index angle. During this action, the tip of the pawl is moved away from the ratchet tooth a sufficient amount to permit the tooth to move under the pawl. The shape of the pawl is designed to form a tip thereon which slides over the tooth during the escape action. The escape does not require extra parts as the pawl is cammed directly against a tooth of the ratchet wheel.

When a pulse is applied to a solenoid, the armature is moved in a first rotational direction, as are the two pawls carried thereon. A first pawl is moved out of contact with the teeth of the ratchet wheel by the cam formed integral therewith. The other pawl slides over the teeth into position for subsequent movement of the ratchet wheel by this pawl upon termination of the pulse. A spring return mechanism provides the power to return the armature and pawls to their neutral position, and the force to move the ratchet wheel one index position during this return.

The present invention further includes a plurality of substantially identical counter modules which together comprise a decade counter. The counter modules each include a count wheel which carries a pulse commutating brush which indexes in a rotational direction with the count wheel. A commutator disc is stationed in close proximity with the count wheel so that the brush thereon makes actual contact with the disc. The commutator disc includes a first set of segments disposed in circular alignment in an inner track and a second set of segments disposed in circular alignment in an outer track which encircles the first track. One contact on the brush is always in contact with the inner track while the other contact on the brush is always in contact with the outer track, thereby serving to bridge predetermined segments in each track.

The respective segments of the inner and outer tracks are arranged in a manner to provide for completion of electrical circuits therebetween in response to the rotation of the ratchet wheel and associated brushes. Circuits are provided to connect both add and subtract input solenoids with the inner track. Further circuits are provided to connect the outer track with both add and subtract solenoids in the next succeeding counter module. The arrangement of the circuits, the commutator, and the segments in each track is such as to provide for transfer of an add pulse to the add solenoids in both the first and succeeding counter modules when the ratchet wheel is in a nine index position. Likewise, the arrangement further provides for transfer of a subtract pulse to the subtract solenoids in both the first and preceding counter modules. Each decade counter module is coupled in this manner. As noted above, no movement of the ratchet wheel or brushes takes place during pulse application. The brushes are moved only after pulse termination.

Additional circuitry is provided to connect a source of counter reset pulses to the subtract solenoid via the inner and outer tracks.

In operation, the application of discrete add input pulses to the first counter module causes the ratchet wheel to index one position forward for each input pulse. The brushes and commutator are positioned so that when the ninth add pulse is terminated, a circuit is completed which enables the next add pulse to step both the first module and the succeeding module one index position forward. Similarly, the application to subtract input pulses to a first counter module causes the ratchet wheel to index one index position backwards for each such pulse. Again, the brushes and commutators are so positioned that when the zero subtract pulse is terminated, a circuit is completed which enables the next subtract pulse to step both the said module and the next preceding module one index position backward.

BRIEF DESCRIPTION OF THE DRAWINGS These and other features and advantages will become more apparent to those skilled in the art when taken into consideration with the following detailed description wherein like reference numerals indicate like and corresponding parts throughout the several views and wherein:

FIG. 1 is a side view of the counter mechanism in accordance with one aspect of this invention which has the cover removed so that the integral parts thereof can be clearly illustrated; and

FIG. 2 is an electrical schematic diagram of the circuitry of the counter shown in FIG. 1 and the commutator transfer discussed therewith.

DESCRIPTION OF ONE PREFERRED EMBODIMENT Turning now to a more detailed description of this invention, there is shown in FIG. 1 a housing 10 which is provided to encase all of the integral parts of the counter mechanism in accordance with one aspect of the present invention. The housing 10 is somewhat rectangular in shape and may be relatively thin. The thinness is preferred when used in modules. A cover, not shown, may be placed over the housing 10 and can serve to carry on the underside thereof the commutator discs hereinafter described. A pair of solenoids 12 and 14 are mounted within the housing 10 and shown in FIG. 2 as 12a, l2b,12N and 14a, 14b, and MN, schematically for each decade in the counter. A magnetic field structure in the form of a three-legged iron core 18 is provided which includes a first leg 19, a second leg 20 and a center leg 22. The coils 12 and 14 are preferably wound around the legs 18 and 20 and are actuated one at a time for either the add or subtract direction. An armature 24, which is pivotally mounted at a pivot 25 to the housing 10, is rotated in a direction dependent upon the field in the cores 18 or 20.

The armature 24 may have a pair of extending arms 38 and 40 therefrom. Mounted on one surface of the armature 24 is a return cam 26 which includes an extending tip 28 which protrudes towards the center leg 22 of the core 18. A pair of springs 30 and 32 are connected onto the center leg 22 of the armature 16 by the retainer screws 36 and 38. These springs 30 and 32 are preferably leaf springs which are adapted to engage the extending tip 28 of the return cam 26 and actually provide the energy for rotating ratchet wheel 46.

The center arm 22 of iron core 16 is a concave structure which matches a convex structure of the armature 24. The legs 18, 20 and 22 provide a magnetic field to the armature 22 when electrical signals are applied to coils 12 and 14. The armature 24 is caused to rotate in a field, with the direction of rotation depending upon which of the coils 12 and 14 is energized.

Pivotally mounted at pivot points 33 and 35 to extension arms 38 and 40, respectively, is a pair of pawls 42 and 44. The pawls 42 and 44 have a downwardly or inwardly extending tip 45 and 47 which are adapted to engage teeth of a ratchet wheel 46 which is pivotally mounted to the housing by a pivot 49. Ratchet wheel 46 has 10 teeth equally spaced about its-circumference. Coupled to the pivot 49 and adapted to actuate with the ratchet wheel 46 is a gear 48. The gear-48 engages a gear 50 which is pivotally mounted by the axle 52 within the housing 10. A number wheel 54 is coupled to the gear 50 and is adapted to rotate therewith. The housing 10 includes an opening or window 56 so that thenumbers on the count wheel 54 may be visually observed therethrough.

Pawls 42 and 44 each includecam means 90 and 92 integrally formed on the inner surfaces of the pawls-42 and 44 so as the ratchet rotates, the cams 90 and92 engage the interfering ratchet teeth, causing the pawl tip 45 to be lifted above the oncoming teeth so that they will not interfere therewith.

If add solenoid 14 is activated, armature 24 is attracted between arms -and 22, causing clockwise rotational movement of armature 24 about pivot 25. Pawls 42 and 44 being carried by armature24, are likewise moved in clockwise fashion about ratchet wheel 46. The tip 45 of pawl 42 does not contact the next adjacent tooth on ratchet wheel 46 because it is cammed overthis tooth by cam 90. The tip 47 on pawl 44 is withdrawn from between the two teeth and moved in between the next adjacent teeth, being retained against the root portion of ratchet wheel 46 by biasing spring 39. Upon removal of the pulse to solenoid 14, the magnetic field in core 16 collapses, allowing leaf spring '30 to rotate armature 24 counterclockwise to its neutral position. Simultaneously therewith, tip 47 of pawl 44, which abuts a tooth on ratchet wheel 46, drives the tooth and ratchet wheel through'a 36 degree increment. Number wheel 54 is likewise driven one index position -via gears 48 and 50.

Similarly, if a subtract pulse were applied to solenoid 12, the exact opposite result would be obtained by a substantially identical but reversed operation.

Turning now to FIG. 2, there is shown a contact switch 110 which is the pulsing contact whereby pulses can be applied to relay switches 112 and 114. The contact switch 110 is shown for schematic purposes only which can be in the form of an oscillator or other type pulse generator which provides a plurality of pulses to which the particular counter circuit of this invention is to record thereon. As can be plainly seen in FIG. 1, brushes 116 are pivoted at '52 and are adapted to rotate equal angularincrements with number wheel 54. Relay switch l l2,'if closed, will cause the counter to count in an add mode with relay switch 114 open. When this happens, the brushes 116, as shown in FIG. 1, will rotate in a clockwise position. If switch 114 is closed and switch 112 is open, the brush 116 rotates in a counterclockwise rotation.

In the specific embodiment disclosed in FIG. 2, a resistor 124 is coupled in series with a diode 126 which are both coupled in parallel across the coil 12a. Likewise, a diode 128 in series which a resistor 130 is coupled in parallel with the coil 140. This circuitry is provided for are suppression to the coils thereby protecting the actuating contacts.

A pair of tracks are provided with an inner track'disposed circumferentially within an outer track. Both tracks are made of an electrically conductive material and are positioned in a manner whereby it is adjacent the wheel 50 shownin FIG. 1. Contact member 148 is in sliding engagement with the track 142 and contact member is in sliding engagement with track 140. The arm 152 leading to contact 148 of brush 116 is longer than the arm 154 leading to contact 150. The contact 150 thus engages the inner track 140 and the contact 148 on arm 152 engages outer track 142.

In a preferred embodiment, the inner track has a first segment 140 extending inabout a 324 degree arc, and a second segment 144 located between the ends of first segment 140. The outer track has a first segment 142 extending in an approximately 188 degree arc. A second segment 158 and a third segment 146 is provided in the'outer track, each of which is located between the ends of the first segment. All segments in the first and second tracks-are electrically isolated from one another. Segment 144 of the inner track is diagonally disposed from segment 146 in the outer track. Segment 158 of the outer track is diagonally disposed from a portion of segment 140 in the inner track. This arrangement enables the bridging of diagonally opposed segments or sections thereof of the inner and outer tracks by the brush assembly 116. Pulse source 120 is connected through add relay 112 to both the add solenoid 12a and the first segment 140 by leads 159 and respectively. Pulse source 120 is also connected through subtract relay 114 to the subtract solenoid 14a and to the second segment 144 by leads 151 and 148 respectively. The second segment 158 of the outer track is connected'to the input line serving as an input of add pulses to the inner track and add solenoid of the next counter module. The third segment of the outer track is connected to the input lineserving as an input of subtractpulses to the inner track and subtract solenoid of the next counter module. The first segment 142 is con nected through a diode 168 to a source of reset pulses provided through relay 164.

lt should be noted that the positioning of the segments in the inner and outer'track are such that when the-count wheel 54 shows a zero in the window 56, the brush 11'6 electrically couples segment 144 to segment 146. When the nine increment on the count wheel 54 is visible from the window 56, the brush 116 electrically couples segment 140 directly to the segment 158.

When the count wheel 54 shows numbers one to eight through window 56, the brush 116 electrically couples segment 140 to segment 142.

Thus, as an add pulse is applied via add relay 112 when count wheel '54 shows numbers one to eight, power-will flow only through add solenoid 12a, which, upon pulse application, rotates the armature 24 to accumulate energy in spring 30. Upon termination of the addpulse, the stored energy in spring 30 returns the armature 2-4 to a neutral position while pawl 44 simultaneously causes ratchet wheel 46 and ultimately number wheel 54 to rotate one index increment, along with brushes 116. Conversely, an opposite rotation takes place if a-subtract pulse were supplied through subtract relay 114, all as was heretofore noted.

When the ninth pulse is received, the armature 24 is cocked while brushes 116 bridge segments 140 and 142. After termination of the ninth pulse, the number wheel rotates to the ninth position, along with brushes 116. No movement of the number wheel 54 or brushes 116 takes place while the add pulse is applied to the circuit. Upon application of the tenth add pulse, armature 24 is again cocked since solenoid 12a energized. I-Iowever, since circuit is now also completed to add solenoid 12b from relay 112 through leads 159, 190, segment 140, brushes 116, segment 159 lead 184 and lead 186, the armature in the next succeeding counter module is simultaneously cocked. Now when the pulse is terminated and solenoids 12a and 12b are deenergized, number wheels on each counter module are advanced one index increment. Subsequent decades are advanced in a like manner. The add circuit to a subsequent decade is only completed after the ninth pulse is received by a preceding decade.

Subtraction is performed in a substantially identical manner. If a subtract pulse is applied to solenoid 14a when brushes 116 are ina zero position (and consequently bridging segments 146 and 144), an electrical circuit is also completed through lead 148, segment 144, brushes 116, segment 146, lead 171 to subtract solenoid 14b in the next counter module. Upon termination of the pulse, the number wheels 54 of both modules are stepped backwards one index position.

Apparatus is included to reset all wheels 54 in each decade to zero, and this is accomplished by closing of a switch 164 which applies positive electrical voltage to segment 142 through a blocking diode 168 and to the segment 170 of disc 160 through a blocking diode 172 and finally through the nth stage to the segment 176 through the blocking diode 178. This then applies electrical energy to all tracks simultaneously through the appropriate brushes 116 in the form of a burst of pulses which continues to pulse the apparatus until the contact 148 of brush 116 reaches the zero segment 146 in disc 138 and segment 180 in disc 160 and segment 182 in disc 162. It can now be noted that all counters are simultaneously pulsed in parallel to cause all count wheels to automatically turn to their zero index position.

Having thus described but one preferred embodiment of this invention, what is claimed and desired to be secured by Letters Patent is:

1. A bidirectional counter comprising a first count wheel,

a second count wheel,

means to rotate said first and second count wheels through one or more index positions selectively in a clockwise direction or a counterclockwise direction,

commutating means,

a brush assembly adapted to be moved in concert with one of said count wheels while simultaneously engaging said commutating means,

a first source of input pulses for rotating the count wheels in a clockwise direction,

a second source of input pulses for rotating the count wheels in a counterclockwise direction,

electrical circuit means for connecting the first and second sources of input pulses to one or more of said means to rotate one or more of said first and second count wheels, depending upon the relative position of the brush assembly and the commutating means, and

means for insuring movement of the count wheels and brush assembly in a clockwise or counterclockwise direction only after disconnection of said electrical circuit means.

2. A counter comprising a first count wheel,

a second count wheel,

means to rotate said first and second count wheels through an index position,

commutating means,

said commutating means including a first plurality of segments disposed in circular alignment in a first track, and a second plurality of segments disposed in a circular alignment in a second track which encircles the first track, means for electrically isolating each of a said first plurality of segments and means for electrically isolating each of said second plurality of segments, said brush assembly adapted to be moved in concert with said count wheels while engaging a segment in said first track and a segment in said second track, a source of input pulses, electrical circuit means for connecting the source of input pulses to one or more count wheels, depending upon the existent interrelationship between the brush assembly and the commutating means, and means for insuring movement of the number wheels and brush assembly only after termination of an input pulse from said source of input pulses. 3. A counter comprising a first count wheel, a second count wheel, means to rotate said first and second count wheels through an index position, commutating means, said commutating means including an inner circular track having a plurality of arcuate segments, an outer circular track encircling said inner track indicates any numeral except nine, further add circuit means for applying add pulses simultaneously to both modules prior to the advance movement of the first module from a nine to a zero indication, subtract circuit means for supplying subtract pulses to only such decade modules which indicate numerals other than zero, and means for maintaining the commutating means and brush assembly stationary during the presence of an add pulse or a subtract pulse. 4. A carry circuit for a bidirectional counter device having at least two decade modules, said circuit includfirst add input means for applying add pulses to the first decade module,

first subtract input means for applying subtract pulses to the first decade module,

second add input means for applying add pulses to the second decade module,

second subtract input means for applying subtract pulses to the second decade module,

commutating means and a brush assembly associated with each module counter,

add circuit means for applying an add pulse to only the first decade module when the first module and having a plurality of arcuate segments,

said segments in the inner and outer tracks being electrically isolated from one another,

said brush assembly being adapted to connect predetermined segments in the inner track with predetermined segments in the outer track,

a brush assembly adapted to be moved in concert with said count wheels while engaging a segment in said first track and a segment in said second track,

a source of input pulses,

electrical circuit means for connecting the source of input pulses to one or more count wheels, depend- 1 ing upon the existent interrelationship between the brush assembly and the commutating means, and

means for insuring movement of the number wheels and brush assembly only after termination of an input pulse from said source of input pulses.

5. The carry circuit of claim 4, wherein said commutating means includes an inner track having first and second electrically conducting segments,

an outer track having first, second and third electrically conducting segments,

said segments all being electrically isolated from one another, whereby said brush assembly is adapted to connect a segment in the inner track with a segment in the outer track.

6. A carry circuit as set forth in claim 5, wherein said further add circuit means includes leads connecting said first add input means to the first segment of the inner track,

and leads connecting said second add input means to the second segment of said outer track.

7. A carry circuit as set forth in claim 6 including a first subtract input means for supplying subtract pulses to the first decade counter,

second subtract input means for supplying subtract pulses to the second decade module,

subtract circuit means for applying subtract pulses to only one decade module when the first module indicates any numeral except zero,

further subtract circuit means for applying subtract pulses to both modules prior to the backward movement of the first module from a zero to a nine indication,

and means for maintaining the commutating means and brush assembly stationary during the presence of a subtract pulse.

8. A carry circuit as set forth in claim 7, wherein said further subtract circuit means includes leads connecting said first subtract input means to the second segment of the inner track,

and leads connecting said second subtract input means to the third segment of said outer track.

9. A carry circuit as set forth in claim 8, including reset means for resetting all counter modules to a zero indication.

10. A carry circuit as set forth in claim 9, wherein said reset means includes a source of repetitive pulses and means connecting the source of repetitive pulses to the first segment of the outer track.

Column 1, line 6, after "1970" insert now abandoned. 11116 32, "seqond" should read second Column 6, line 3, "member 140" should read member 150 v v UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,778,600 Dated D c r 1, 1973 Inventor) John S Burton It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the Claims:

Claim 3 A counter comprising a first count wheel,

a second count wheel,

means to rotate said first and second count wheels through an index position,

commutating means,

said-commutating means including an inner circular track having a plurality of' arcuate segments,

an outer circular trackencircling said inner track and having a plurality of arcuate segments.

said segments in the inner and outer tracks being electrically isolated from one another,

a brush assembly being adapted to connect predetermined segments in the inner track with predetermined segments in the outer track,

USCOMM-DC 603764 69 FORM PO-1050 (10-69) m y I ursr sovzmmzm PRINTING orncz; was o-sss-au.

P 3 ,778,600 Dated December 11, 1973 Inventor) John 8. Burton Page 2 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

said brush assembly adapted to be moved in concert with said count wheels while engaging a segment in said first track and a segment in said second track,

a source of input pulses,

electrical circuit means for connecting the source vof input pulses to one or more count wheels, depending upon the existent interrelationship between the brush assembly and the commutating means, and

means I for insuring movement of the number wheels and brush assembly only after termination of an input pulse from said source of input pulses.

Claim 4. carry circuit for a bidirectional counter device having at least two decade modules, said circuit including first add input means for applying add pulses to the first decade module, v

first subtract input'means for applying subtract pulses to the decade module,

second add input means for applying add pulses to the second decade module, I

second subtract input means for applying subtract pulses to the second decade module,

FORM Po-105O (10-69) a v USCOMM-DC 6O376-P69 U. 5 GOVERNMENT PRINTING OFFICE-2 I969 0-366-335,

UNITED STATES PATENT OFFICE v CERTIFICATE OF CORRECTION I Patent NO; 22 Dated December 11 1973 lnventofls) v John S Burton Page 3 It is certified that'error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

means and a brush assembly associated with each module counter,

I add circuit means for applying an add pulse to only the first decade module when the first modple indicates any numeral except nine; 7 I I Q further add circuit means for applying add Pulses simultaneously to both modules prior to the advance movement of the first module from a nine to a zero indication,

I subtract circuit means for supplying subtract pulses to only such i deca de modules which indicate numerals qther than zero 7 Q and means for maintaining the comxmltatin91v means and I brush assembly stationary during the presence an add pulse or a subtract. pulse.

" Signed and sealed this 16th day f July 1974.

(SEAL) Attest:

C.'MARSHAL:L'-DAN N' McCOY M. GIBSON, JR.

Commissioner of Patents- Attesting Officer FORM po-wso (10-69) I comb-Dc 60:57am" I U,$. GOVERNMENT PRINTING OFFICE lllO-JGI-JJJ. 

1. A bidirectional counter comprising a first count wheel, a second count wheel, means to rotate said first and second count wheels through one or more index positions selectively in a clockwise direction or a counterclockwise direction, commutating means, a brush assembly adapted to be moved in concert with one of said count wheels while simultaneously engaging said commutating means, a first source of input pulses for rotating the count wheels in a clockwise direction, a second source of input pulses for rotating the count wheels in a counterclockwise direction, electrical circuit means for connecting the first and second sources of input pulses to one or more of said means to rotate one or more of said first and second count wheels, depending upon the relative position of the brush assembly and the commutating means, and means for insuring movement of the count wheels and brush assembly in a clockwise or counterclockwise direction only after disconnection of said electrical circuit means.
 2. A counter comprising a first count wheel, a second count wheel, means to rotate said first and second count wheels through an index position, commutating means, said commutating means including a first plurality of segments disposed in circular alignment in a first track, and a second plurality of segments disposed in a circular alignment in a second track which encircles the first track, means for electrically isolating each of a said first plurality of segments and means for electrically isolating each of said second plurality of segments, said brush assembly adapted to be moved in concert with said count wheels while engaging a segment in said first track and a segment in said second track, a source of input pulses, electrical circuit means for connecting the source of input pulses to one or more count wheels, depending upon the existent interrelationship between the brush assembly and the commutating means, and means for insuring movement of the number wheels and brush assembly only after termination of an input pulse from said source of input pulses.
 3. A counter comprising a first count wheel, a second count wheel, means to rotate said first and second count wheels through an index position, commutating means, said commutating means including an inner circular track having a plurality of arcuate segments, an outer circular track encircling said inner track indicates any numeral except nine, further add circuit means for applying add pulses simultaneously to both modules prior to the advance movement of the first module from a nine to a zero indication, subtract circuit means for supplying subtract pulses to only such decade modules which indicate numerals other than zero, and means for maintaining the commutating means and brush assembly stationary during the presence of an add pulse or a subtract pulse.
 4. A carry circuit for a bidirectional counter device having at least two decade modules, said circuit including first add input means for applying add pulses to the first decade module, first subtract input means for applying subtract pulses to the first decade module, second add input means for applying add pulses to the second decade module, second subtract input means for applying subtract pulses to the second decade module, commutating means and a brush assembly associated with each module counter, add circuit means for applying an add pulse to only the first decade module when the first module and having a plurality of arcuate segments, said segments in the inner and outer tracks being electrically isolated from one another, said brush assembly being adapted to connect predetermined segments in the inner track with predetermined segments in the outer track, a brush assembly adapted to be moved in concert with said count wheels while engaging a segment in said first track and a segment in said second track, a source of input pulses, electrical circuit means for connecting the source of input pulses to one or more count wheels, depending upon the existent interrelationship between the brush assembly and the commutating means, and means for insuring movement of the number wheels and brush assembly only after termination of an input pulse from said source of input pulses.
 5. The carry circuit of claim 4, wherein said commutating means includes an inner track having first and second electrically conducting segments, an outer track having first, second and third electrically conducting segments, said segments all being electrically isolated from one another, whereby said brush assembly is adapted to connect a segment in the inner track with a segment in the outer track.
 6. A carry circuit as set forth in claim 5, wherein said further add circuit means includes leads connecting said first add input means to the first segment of the inner track, and leads connecting said second add input means to the second segment of said outer track.
 7. A carry circuit as set forth in claim 6 including a first subtract input means for supplying subtract pulses to the first decade counter, second subtract input means for supplying subtract pulses to the second decade module, subtract circuit means for applying subtract pulses to only one decade module when the first module indicates any numeral except zero, further subtract circuit means for applying subtract pulses to both modules prior to the backward movement of the first module from a zero to a nine indication, and means for maintaining the commutating means and brush assembly stationary during the presence of a subtract pulse.
 8. A carry circuit as set forth in claim 7, wherein said further subtract circuit means includes leads connecting said first subtract input means to the second segment of the inner track, and leads connecting said second subtract input means to the third segment of said outer track.
 9. A carry circuit as set forth in claim 8, including reset means for resetting all counter modules to a zero indication.
 10. A carry circuit as set forth in claim 9, wherein said reset means includes a source of repetitive pulses and means connecting the source of repetitive pulses to the first segment of the outer track. 